The present invention relates to a boom for a boardsailing.
A conventional boardsailing includes a mast attached to the body of the board by a universal joint, a boom attached to the halfway portion of the mast, and a sail attached to the mast and the boom and spread along them so that the sail can be manipulated. The boom is made of two bodies curved outward away from each other and connected to each other at both ends of the bodies so that the boom has an endless form. One end of each of the bodies of the boom is fitted in a coupler for the bodies, and pins provided on the body are engaged in optional ones of the holes of the coupler, so as to connect the body and the coupler to each other and set the boom at a desired length in accordance with the size of the sail, which is interchangeable depending on the strength of the wind on the sail. The boom is made of an aluminum alloy.
A boom made of an aluminum pipe reinforced by resin layers provided on the inside and outside surfaces of the pipe and reinforced by carbon fibers was developed in order to reduce the weight of the conventional boom for boardsailing without decreasing the strength thereof, as disclosed in the Japanese Utility Model Application (OPI) No. 13396/84 (the term "OPI" as used herein means an "unexamined published application"). However, it is desirable to reduce the weight of the boom even further to enhance the steering property of the boom. The enhancement can be achieved making the entire body of a carbon-fiber-reinforced resin or the like rather than aluminum. However, since the bodies have pin holes or rivet holes at their front ends and engagement pin holes at the rear ends thereof, and these holes need to be located in mutually symmetric opposite positions on the diameters of the bodies, the strength of the portions of the bodies, which have the holes, is greatly decreased. This is a problem.